1. Field of the Invention
The present invention, in general, relates to devices that are used to manually transport cargo items and, more particularly, to backpacks.
Backpacks are well known types of outdoor equipment. They are used by hikers to transport clothing, food, and shelter to and from remote locations. Certain smaller, lighter duty types of backpacks are constructed entirely of fabric and do not require any supporting type of frame structure.
However most conventional types of backpacks that are used to satisfy heavier duty types of cargo transportation requirements rely upon a cooperating frame type of structure. The frame is usually constructed of either aluminum, graphite, or titanium tubing, or the like, and is designed so as to cooperate with a fabric shell.
The frame is either located inside the fabric shell or it may be located external to the fabric shell and is fastened thereto. A method of securing the backpack about the waist is usually provided along with support straps that pass over the shoulders of the user. The fabric shell of most conventional types of backpacks will contain one or more compartments for the storage of goods that are to be transported.
There are two limitations that are generally shared by such types of backpacks. Conventional types of backpacks are inherently limited with regard to both the maximum size or bulk and the maximum amount of weight of the cargo items that can thus be transported.
The maximum weight capacity is limited by the structure of the backpack and by the strength of the user. Most users do not feel comfortable if their loaded backpack weighs more than about one-third of their own body weight.
Therefore a 150 pound hiker would most likely find it uncomfortable to transport over 50 pounds in his backpack and would find it almost unbearable to transport 150 pounds in his backpack, assuming of course that there was sufficient compartmental room in the backpack to house that much weight of cargo. Consequently, in order to allow for the transportation of very heavy loads, a device having wheels is usually preferred by most users.
The size of the cargo that may be transported is limited, in general, to that which can be stored (fit) within the fabric shell compartments. Certain items, such as sleeping bags or fishing poles, are occasionally strapped to the exterior of the backpack.
However, certain very large items are too awkward to transport in or even on a conventional backpack. If a very large item were to be fastened to the exterior of a backpack it would be difficult to maneuver about in timber with the item protruding from the backpack.
Furthermore, a bulky heavy item strapped to the exterior of a conventional type of backpack affects the center of gravity adversely. This is because the bulky item tends to move the center of gravity further away from the spine of the user. In order to maintain balance the user is compelled to lean forward. If a heavy enough item is placed in or on a backpack and is situated far enough away from the spine of the user, the user cannot stand erect but will be forced to lean too far forward to feel comfortable while either standing or walking.
There are numerous occasions that arise when it is desirable to use a backpack for the transportation of large or heavy items. For example in remote wilderness group or base campsites, it is desirable to be able transport large tents, supplies, and the like to the site. These items may remain at the base campsite for extended periods of time while the inhabitants occasionally leave for and return from various excursions.
Therefore a backpack that is capable of transporting very large items to the campsite is a useful device. Ideally such a backpack would then readily adapt to accommodate smaller items, such as the clothing and foodstuffs that are used during the daily excursions.
In addition it is sometimes necessary when returning from hiking expeditions to be able to transport much heavier cargo items than were initially carried into the field. Such an example is clear to anyone who has had a companion become immobilized by an injury while in remote areas. A companion hiker who sprains an ankle or even worse, breaks a leg, for example, will need to be assisted out of the wilderness. A backpack that can adapt, when necessary, to satisfy such a purpose is desirable for hikers, campers, hunters, and field workers, and would also provide benefit to search and rescue personnel as well.
Another similar type of need is experienced by big game hunters who travel on foot. Such hunters may spend days in the field without success. While they travel by foot they often utilize a backpack to carry the extra clothes, food, and supplies that they require during the day while hunting. However when they are successful in killing a deer, elk, or the like a device that is useful to aid in transporting the game animal out of the woods is then required. Carts have been devised to satisfy this purpose however most hunters prefer not to transport such types of carts into the woods for reasons of vanity as the utility of such types of carts is obvious even when unladen.
While the need for an improved backpack is clearly desirable, most users will continue to prefer a more traditional looking type of backpack while they are on foot. If the need to transport a particularly large or heavy item arises, the visual aesthetics become far less important while the functional ability to transport such types of items is elevated in importance. Therefore an improved backpack that is generally traditional in appearance when it is used for the transport of small or light cargo items is preferred.
Accordingly there exists today a need for an improved backpack that is capable of functioning similar to conventional backpacks and, when desired, is readily convertible into a wheeled cart that is useful to transport especially heavy or bulky cargo items.
2. Description of Prior Art
Backpacks and carts, in general, are known. For example, the following patents describe various types of collapsible carts and back carried carts:
U.S. Pat. No. 547,288 to Remington, Oct. 1, 1895; PA1 U.S. Pat. No. 2,401,986 to Talbot, Jun. 11, 1946; PA1 U.S. Pat. No. 2,918,296 to Goodale, Dec. 22, 1959; PA1 U.S. Pat. No. 3,054,622 to Davis et al, Sep. 18, 1962; PA1 U.S. Pat. No. 3,236,537 to Eckman, Feb. 22, 1966; PA1 U.S. Pat. No. 3,860,254 to Wegener, Jan. 14, 1975.
While the structural arrangements of the above described devices, at first appearance, have similarities with the present invention, they differ in material respects. These differences, which will be described in more detail hereinafter, are essential for the effective use of the invention and which admit of the advantages that are not available with the prior devices.